How do ESF / KCIS and Victoria compare

We have to pick a kindergarten for our son. Could you please share your views on ESF, Kiangsu Checkiang International Section (KCIS) and Victoria. One of the most important things for us is that he grows up billangual in English and Mandarin.

My sons went to both Vic and KCS. Both are greta. Vic is less traditional and has 50% Mandarin and 50% English. KCS is more traditional with 90% Mandarin and 10% English. The teachers in both schools are great but there are heaps of homework from Vic, even at K1 level. We contemplated ESF initially but as they only offered mainly English and we did not want to separately send the boys to Mandarin classes after school, we decided on Vic and KCS - one for each boy.